I. Field of the Invention
The present invention relates to conveyor systems.
II. Description of the Prior Art
There are many previously known conveyor systems. In one type of conveyor system, rollers engage work pieces supported on the conveyor system in order to propel the work pieces from one end of the conveyor system and toward the other end. In many cases, one or more work stations are positioned along the conveyor line in order to perform work of one sort or another upon the work pieces.
These previously known roller conveyor systems typically propel the work pieces along a generally horizontal plane. In some instances, such as the assembly of an automotive body, it is desirable or even necessary to elevate the work piece above the plane of the conveyor line at a particular work station and before the work is performed on the work piece.
In order to accomplish the elevation of the work piece at a particular work station, it has been the previously known practice to provide a lifter assembly beneath the conveyor line at the work station. Thus, once the work piece is conveyed to the work station, activation of the lifter assembly elevates the work piece from a lower and to a raised position. These previously known lifter assemblies typically engage preset location points on the work piece.
While these previously known lifter assemblies have proven adequate where the work pieces are identical to each other, and thus have identical location points for the lifter assembly, in some cases, different types of work pieces having different location points for the lifter assembly are conveyed on a common conveyor line.
One such example of this latter case is in the assembly of the body for automotive vehicles. In such conveyor lines, the automotive bodies are initially supported on a skid which is conveyed down the conveyor line. However, since different automotive bodies may be conveyed by a common conveyor line, it is oftentimes necessary to provide different lifter assemblies at a single work station in order to accommodate these different automotive bodies.